In recent years, the use of mobile devices, particularly smartphones and tablets, has grown significantly. A number of techniques have been proposed and several systems have been developed and deployed using visual light communication (VLC) from lighting devices to provide information to the mobile devices, for example, to allow the mobile devices to determine estimates of their respective positions in a venue illuminated by the lighting devices and to utilize information about the identified location to assist a user of the mobile device. For example, the mobile device may display a map of an area in which the mobile device user is currently located as well as an indication of the user's location on the map. In this way, the user may utilize the mobile device as a navigational tool, for example.
Traditionally, a mobile device may use location identification services such as Global Positioning System (GPS) or cellular communications to help identify a current location of the mobile device. However, GPS and cellular communications may not provide sufficient information when the mobile device is located within a building, and suffer from multi-path propagation effects that make it unsuitable for indoor environments. More recently, the mobile device may use Wi-Fi and/or other radio frequency (RF) technologies (e.g., Bluetooth, Near-Field Communications (NFC), etc.) to help identify the current location of the mobile device within a building. But such Wi-Fi and RF based solutions may be slow and may require that additional infrastructure, such as hotspots or beacons, be added within the building. This additional infrastructure has additional costs that may not be outweighed by any benefit provided to the user of the mobile device. There are advantages of VLC or other light based positioning over other mobile device position determination technologies, particularly for indoor position determinations. For example, optical techniques, such as VLC, are more accurate and/or reliable since light waves are highly directional and do not pass through most materials. Therefore, a light-detecting device can be presumed proximate to a light source if the source is robustly detectable. Additionally, the location identification services have most often been useful in bright, well-lit environments.
VLC transmissions from lighting devices may have communication applications instead of or in addition to transmitting data for use in position estimation. VLC transmissions, for example, may carry text information about items of interest or services available in the venue. For most mobile device applications, reception of VLC relies on a rolling shutter camera normally included in the mobile device to capture images of light sources. The circuitry of the mobile device processes the images to detect data modulated on the light output from the light sources.
A need exists for providing improved VLC reception in a dark or low surrounding light setting within a building or outdoors at dusk/night with minimal delay and without requiring additional infrastructure.